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Aquatic Plants and the Environment (SWES, ECOL, WFSc 474/574)

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Presentation on theme: "Aquatic Plants and the Environment (SWES, ECOL, WFSc 474/574)"— Presentation transcript:

1 Aquatic Plants and the Environment (SWES, ECOL, WFSc 474/574)
Constructed Wetlands Dr. Kevin Fitzsimmons Professor – University of Arizona

2 Terminology of constructed wetlands
1. Restored wetlands - those under rehabilitation. Put back into working order (fixed) hydrology of wetland either by dredging or by taking out a dike (common in small areas). 2. Constructed wetlands - built where none existed before (usually for water treatment). Usually well engineered. 3. Created wetlands - developed where none existed before (usually for wildlife habitat). Normally done with little engineering.

3 Reasons for constructed wetlands
1. Waste Treatment 2. Hydraulic modification - for flood control, water storage 3. Water quality changes 4. Erosion protection 5. Open spaces and aesthetics 6. Mitigation 7. Habitat for wildlife

4 1. Waste Treatment Municipal waste (sewage): secondary/tertiary treatment of wastewaters. To reduce the nitrogen, phosphorus, TSS (Total Suspended Solid), BOD (Biological Oxygen Demand), TFC (Total Fecal Coliforms). CAFO treatments (Concentrated Animal Feeding Operations): treat wastes from dairies, feedlots, hog sheds, chicken ranches, and fish farms.

5 1. Waste Treatment Acid Mine Drainage: Absorb heavy metals and increase the pH. Highway Runoffs: Effective for cleaning the water that runs off roads carrying oil, gas, dirt, etc. Specific Pollutants: Wetlands put in to treat or absorb a heavy metal or organic. Often, the plants will accumulate chemicals inside the plant stem and leaves (concentrating the pollutants). The plant can then be disposed of. Storm Water: Handle storm waters in developed areas where runoff is a problem. Cleans up runoff as well.

6 2. Hydraulic modification
Flood control – reduce flood waters and impacts Water storage – reservoir Groundwater recharge

7 3. Specific water quality changes
Reduce sediment loading Raise or lower extremes of pH Add or remove organics (remove in the case of paper mills, add in acid mine drainage).

8 4. Erosion and flood protection
Bank or shoreline stabilization Dissipation of wave energy Dissipation of flood flows Alter flow patterns of stream or river

9 5. Open spaces and aesthetics
Used by resorts or new developments to increase land value. Adds nature values Property owners will pay extra for sounds, smells and sights of wildlife and wetland plants

10 6. Mitigation Intended to replace the function of lost wetlands.
In US, when developers destroy wetlands they must replace them by a 1 to 2 or 1 to 3 ratio. The developer is not only responsible for replacement, but the function as well. Usually replaced wetlands do not function as well. Lots of problems occur with how to build and maintain them.

11 7. Habitat as life support
Habitat specifically for threatened and endangered species Habitat for other wildlife.

12 Design of constructed wetlands
 A. Free water surface systems (FWS): have open water surfaces, water is exposed, covering the substrate, submerged and emergent plants.  B. Subsurface flow systems (SFS): water below surface level, the substrate is exposed to air at the surface. Only emergent plants        

13 Design of constructed wetlands
 A. Free water surface systems (FWS): have open water surfaces, water is exposed, covering the substrate, submerged and emergent plants.  B. Subsurface flow systems (SFS): water below surface level, the substrate is exposed to air at the surface. Only emergent plants        

14 Typical construction for a small sub-surface wetland

15 Constructed wetlands can be customized for the task
Select submerged flow or free surface Determine volume of anaerobic vs aerobic needed Select plants that will accomplish task - fast growing plants that scour nutrients - plants that bio-accumulate heavy metals - plants that accumulate or break down organics - plant community that drops leaves to add organics to water

16 Typical subsurface flow systems
Treating grey water from a house in Italy Treating municipal waste in Virginia, USA

17 Typical free water surface flow
Farm animal waste treated In Pennsylvania, USA Municipal waste treated In Florida, USA


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